To play in split-screen do the following:
- Once all the controllers* are connected, launch Rocket League
- While in the Main Menu, Player 2 needs to press:
- DualShock 4 Controller Options button
- Xbox One Controller Menu button
- Steam Controller Start button
- Player 2 will then join the party and you can play any Offline or Online mode together
*Note: In order to play Split-Screen on PC you need two controllers. Keyboard/Mouse + controller is not officially supported.